1. Field of the Invention
The present invention relates to a seat reclining apparatus, and more particularly to a seat reclining apparatus that is capable of insulating an uncomfortable sound which may be caused by a vibration during vehicle running.
2. Description of the Prior Art
Hitherto, various types of seat reclining apparatuses have been proposed and put into practical use particularly in the field of motor vehicles in order to secure a good driver""s seating condition.
Each seat reclining apparatus has a pair of seat reclining devices, one of which is provided on the right side of the seat cushion and the other of which is provided on the left side of the seat cushion. For interlocking the pair of seat reclining devices, an operation lever is disposed on either the right side or the left side of the seat cushion.
Japanese Patent Unexamined Publication JP 10-71040 discloses a seat reclining apparatus. In this apparatus, a pair of a first and a second link plates are secured to both ends of an interlocking shaft. The interlocking shaft is substantially orthogonal to the link plates. A pin is projectively disposed at a substantially end portion of the operation lever, and passes through an elongate opening of the first link plate. Another pin projects through a cam member and an elongate opening of the second link plate.
However, there used to occur the following uncomfortable sounds that are attributable to vibrations during vehicle running: A sound caused by an abutment of the pin against the inside edge of the elongate opening of the link plate. In addition, a sound caused by the operation lever that occurs when the operation lever is returned after it has been lifted up.
It is, therefore, an object of the present invention to provide a seat reclining apparatus that is capable of insulating vibration sound.
According to the present invention, there is provided a seat reclining apparatus which comprises a pair of base plates adapted to be secured to a seat cushion; a pair of arm plates adapted to be secured to a seat back, for allowing a pivotal movement of the seat back; an interlocking shaft for allowing a pivotal movement of the pair of arm plates at substantially the same time relative to the pair of base plates; a link plate formed on the interlocking shaft, the link plate having an opening; a sound-insulating member attached to the link plate, the sound-insulating member having an opening and an inside edge defined by the opening thereof, the inside edge projecting more inwardly than an inside edge defined by the opening of the link plate; and a pin for allowing one of the arm plates to pivot by a movement of the pin, the pin being disposed to pass through the opening of the link plate such that the pin is allowed to abut against the inside edge of the sound-insulating member when the link plate is rotated by the interlocking shaft.